I have had my toledo v5 2.3l 170 BHP for a few weeks now and the diagnostic warning light appeared on the dash yesterday. When I had the car scanned at the garage the fault code in the system was 17559 (p1151). The garage reset the code and it hasn't reappeared in the 20 mile trip back home?

I have found the information on the fault code on Ross Tech.

What is the best way to test and eliminate each sensor? The car almost feels as though it has a very slight misfire. It has been like this since day one of my ownership and I assumed it was because of the v5 engine configuration that caused the slight shaking on idle. Is that normal?

Resetting the fault code also resets the fuel trim, which is what the fault code is. It'll come back eventually once the fuel trim has caught back up with the readings. It took about 50 miles for my mates fuel trim to settle back to normal.

Personally the first thing I would look at is all the pipework at the back of the engine, between the throttle body and the engine. In particular there is a corrugated pipe that sits on top of the throttle body, and feeds into the cylinder head. It's very common for that pipe to split, and as soon as unmetered air gets into the system the fuelling goes to hell.

If everything looks ok there, get your car to a garage and get them to check the emissions. It's possible that one of the lambda sensors is giving false readings.

The V5 can feel 'lumpy' due to the design, however it can also feel lumpy if a coilpack is starting to fail. But they generate their own fault code so don't worry about those for now.

I have had a looked around the engine for split pipes and I have found one! Although I couldn't see any corrugated pipes? (can you point out the location in the pictures below if possible?) I have attached some picture (sorry for poor picture quality!) to show you what pipe is split is this the likely causes? The pipe runs into the back of what I'm assuming is the black plastic inlet mainfold?

Defo sounds like the front lambda sensor failing. If the pipework is all clear I would do as Slimy says and get a replacement. I recently replaced mine as a precaution too, about £70 from parts suppliers.

Huh, crossed paths there. If you have some duct tape try sealing the holes, atleast temporarily. The pipe Slimy was referring to is the one in your bottom picture about 3inches right of the throttle body, the one that joins back into the air intake.

I think, think, it might be connected to the N80 solenoid valve, which is something to do with the cabin filter, maybe it is meant to detect if there is too many harmful gases entering the cabin via the filter? Only a guess though. If that is the case then I don't think that would be the cause of the misfire.

I think, think, it might be connected to the N80 solenoid valve, which is something to do with the cabin filter, maybe it is meant to detect if there is too many harmful gases entering the cabin via the filter? Only a guess though. If that is the case then I don't think that would be the cause of the misfire.

That would make sense as the pipe goes into the cabin. As long as its not letting air into the air intake system I cant see how it would effect the fault code that I have.

I will recheck the other pipes tomorrow in the daylight. Otherwise I guess it's looking like the pre cat oxygen sensor? How easy is it to change?

I agree with Krisby, that particular pipe may not be the problem. I'd probably tape that up anyway, a hole in any pipe can't be good.

The corrugated pipe is dead centre of the second photo, it goes from that silver box and is smooth for the first four inches, then turns into a corrugated pipe to make the tight corner. I should mention that I didn't know mine was broke until I moved it, from outward appearance it looked fine.

The oxygen sensors are fairly easy to change, you just need a good spanner and the ability to get right underneath the car. They're not particularly cheap though, that's why I suggested getting an exhaust gas analysis done at an mot station. Then again, if they charge by the hour that could be just as expensive!

N80 is the charcoal filter solenoid valve. The charcoal filter is part of the fuel tank vent system: it absorbs fuel vapours while the car is not running and opens to allow them to be sucked into the inlet system when the car is running and up to temperature. (We're not allowed to emit any unburned hydrocarbons in case California should run out of breathing air).

The line you've shown isn't heading anywhere near the charcoal filter, which is on the nearside wing between the washer bottle and the cooling system header tank. The charcoal filter vents into the crankcase breather hose.

I don't have a V5 so am not familiar with the plumbing - however, if, as I think, that pipe is attached to the inlet manifold on the left, then it is part of the pneumatic system, and is tapping the inlet manifold for vacuum (have you got any pictures with more detail, more pixels so we can see a bit closer?). With holes in the vacuum pipe you are letting unmetered air into the inlet manifold after the throttle body, so it's uncontrolled as well. The ECU will be having a fit.

You've also compromised the vacuum source, so there won't be as much vacuum as there should be (This is a horrible statement: vacuum is an absence of air pressure. What I really mean is there's a hole in the pipe leading to where the engine is sucking air in, so there's not so much suck. If you see what I mean) Lack of vacuum will affect the brake servo and anything else that's vacuum-powered on your car. That will include the secondary air inlet valve N112, the fuel pressure regulator and the intake manifold changeover valve N156 (changes the manifold length).

As to where it's going, I think I can see a T-piece next to the throttle body, possibly heading off towards the brake servo or vacuum reservoir. The N112 and N156 valves appear to be mounted at the front of the engine bay next to the inlet ports, and the fuel pressure regulator is down there as well.

If this is the vacuum hose you really need to get it fixed, and find out why it's in that state in the first place, to stop it happening again.

Slight misfire, and shaking at idle? Something very wrong here, the V5 engine is the epitome of smoothness. Eliminate the vacuum system first. It may be a good idea to reset the ECU by disconnecting the battery for half and hour or so - make sure you have the security code for the radio first, though. When you reconnect the battery the car will run like a dog to start with as all the ECU adaptions will have been forgotten. Take if for a few short drives, switching off between each one, and including some national speed limit mileage. The ECU will re-learn the adaptions, and will hopefully run a lot better. If you still have misfiring, the next suspect is coil packs.

I agree with Krisby, that particular pipe may not be the problem. I'd probably tape that up anyway, a hole in any pipe can't be good.

The corrugated pipe is dead centre of the second photo, it goes from that silver box and is smooth for the first four inches, then turns into a corrugated pipe to make the tight corner. I should mention that I didn't know mine was broke until I moved it, from outward appearance it looked fine.

The oxygen sensors are fairly easy to change, you just need a good spanner and the ability to get right underneath the car. They're not particularly cheap though, that's why I suggested getting an exhaust gas analysis done at an mot station. Then again, if they charge by the hour that could be just as expensive!

The sensor is £70 or £50 for the emission test so I might as well change it and see what effect is has on the car as its going to need doing soon anyway. Where is the plug/connector for the oxygen sensor? I can see where the sensor is and when I follow the wiring it goes up to the driver side of the engine bay but I cant see a plug/conector to unplug the wiring and plug the new one in. My local motor factors seems to think the sensor is on a 6pin plug but I cant see any plugs that big in the engine bay?

I would say so. I monitored mine through an app on my phone. If you have android and a spare £15 get yourself Torque off the android market and an OBDII bluetooth connector for the car, it will save you hundreds.